Two government reports reveal the sleep habits of adults in the U.S.

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Two reports released by the Centers for Disease Control and Prevention Thursday reveal the sleep habits of adults in the United States, including their increasing tendency to get fewer than seven hours a night, hurting their ability to concentrate and raising the risk of driving.

Residents of Hawaii have particular trouble sleeping well, according to the responses to one survey, and the CDC said more research on the matter is needed.

In one report, based on a survey of nearly 75,000 people in 2009, CDC researchers examined four unhealthy sleep behaviors: inadequate sleep, snoring, nodding off during the day and nodding off while driving.

Thirty-five percent reported getting fewer than seven hours of sleep on an average night, 48 percent reported snoring, 38 percent reported unintentionally falling asleep during the day sometime in the previous month, and nearly 5 percent said they'd nodded off while driving in the previous month.

The number of U.S. adults reporting that they get fewer than seven hours of sleep rose from 1985 to 2004, and that increase could be attributed to trends such as the increased use of technology and more people working night shifts, the CDC said.

Among people ages 25 to 54, nearly 40 percent reported getting fewer than seven hours of sleep. People over 65 were the least likely to say they got fewer than seven hours of sleep — about 25 percent of them reported this.

About 46 percent of those currently unable to find work said they got fewer than seven hours of sleep, compared with 37 percent of employed people. And, of the 12 states in which adults were surveyed, Minnesota had the lowest rate (27 percent) of residents who got fewer than seven hours of sleep, while 45 percent of Hawaiians said the same.

And people ages 25 to 34 were the most likely to say they'd fallen asleep while driving sometime during the last month. Seven percent of them did, compared with just 2 percent of seniors, who were least likely to report this behavior. Nearly 6 percent of men said they'd done this, while 3½ percent of women had.

Drowsy driving is one of the most lethal consequences of inadequate sleep, the CDC noted. According to the Department of Transportation, it's responsible for an estimated 1,550 deaths and 40,000 injuries each year in the United States.

To promote healthy sleep behaviors, increased public health awareness of sleep quality, behaviors and disorders is needed, as well as training in sleep medicine for healthcare professionals.

The second report examined the effects of getting too little sleep on daily activities. That report was based on data from two surveys, conducted between 2005 and 2008, including almost 11,000 respondents.

Among the six daily activities included in the survey, the ability to concentrate was the most commonly reported difficulty associated with too little sleep. About 29 percent of adults who got fewer than 7 hours of sleep a night said they had a hard time concentrating, while just 19 percent of those getting 7 to 9 hours of sleep a night reported this.

Those who reported sleeping less than seven hours also had greater difficulties remembering things, participating in hobbies, driving or taking public transportation, taking care of financial affairs and working than did those who reported getting 7-9 hours a night.

There are several limitations in interpreting the reports' results, the CDC said. For example, the first included only households with telephone landlines in 12 states, and both studies were based on self-reported data.